Abstract ID: 17332 Title: Ultrasound-Guided Techniques for HIFU Monitoring
HIFU is the only truly noninvasive and non-ionizing tumor treatment method. Unlike RF
ablation, HIFU does not require interstitial tissue incision or needle insertion, but instead induces
heat extracorporeally. Several methods have been developed for efficient HIFU monitoring. In
ultrasound-guided methods, the HIFU lesion can be detected when cavitation or boiling occurs
due to the high bubble concentration that causes high echo amplitudes. Tissue coagulation also
results in the increase of tissue attenuation, which has also been shown to efficiently map the
lesion size when attenuation is estimated. Another technique that combines the resulting well
known optical opacity of the resulting lesion and ultrasound is the opto-acoustic technique that
has been shown to determine the lesion formation. Finally, tissue coagulation has been
associated with significant changes (2-10 times) in tissue stiffness. Elastography uses a small
external compression in the detection of HIFU-induced lesions after formation ex vivo.
Harmonic Motion Imaging (HMI) uses a focused ultrasound (FUS) beam to generate an
oscillatory acoustic radiation force for an internal, non-contact palpation to simultaneously
internally estimate relative tissue stiffness and induce thermal damage. HMI has been shown to
be successful in monitoring and assessing the formation of a lesion both ex vivo and in vivo.